kalali, did I not already say don't overthink it? And then you go and compliment and start paying attention to the world's greatest offender in overthinking it? Now it appears you have overthought things to the point you've concluded that what works for everyone else cannot possibly work for you. At least that is what you think. Because you are thinking. Instead of doing....
... Please go back and read my first post. Then stop thinking about impedance. Start thinking about table saws, sand papers, and veneers.
Miller, my analysis establishes pretty conclusively that the OP's preamp should not be used to drive four powered subs having typical impedances, in addition to his power amp. That was something he was rightfully concerned about, and that he had specifically asked about.
Rather than telling him to "stop thinking about impedance," and throwing in a gratuitous insult (toward me) in the process, I suggest that it would be more constructive if you were to specifically address the question he and I were discussing, about driving all of those loads with his particular preamp.
Regards,
-- Al